There is known a power conversion device for converting DC voltage to AC voltage for output to a power system. The DC voltage is inputted from a DC voltage source such as a solar cell panel. In the power conversion device, upon an instantaneous voltage drop on the power system, overcurrent may occur at the output and stop the operation. For instance, in the case where a large number of power conversion devices are connected to the power system, simultaneous stop of the power conversion devices may lose the balance of power supplied to the load. This may make the power system unstable. In this context, there is known a power conversion device as follows. An instantaneous voltage drop is detected based on the system voltage. The output is temporarily stopped to continue the action. Thus, abrupt change in the power system is suppressed. However, in the case of detecting an instantaneous voltage drop based on the system voltage, there is concern about unnecessarily decreasing the output.